In accordance with present practice, resin locking patch material is applied to fasteners by passing the fasteners in heated condition through a stream of thermoplastic resin particles or powder carried in a blast of air from a jet nozzle. The powder accumulates on the hot fasteners and fuses into a body or patch of thread locking material. However, the air stream has a chilling effect on the fasteners, increasing production time and energy needed to heat the fasteners. Examples of apparatus for applying patch material to fasteners are shown in U.S. Pats. Nos. 3,498,352; 4,120,993 and 4,508,759.